Structure and mechanism of action of phospholipase A2 from venoms and human plasma will be determined. The physiological role of human phospholipase in plasma and tissues will be investigated. Biosynthesis, transport, catabolism and mechanism of action of insect juvenile hormone will be investigated. Control of biosynthesis, structure and binding specificity and physiological function of a specific juvenile hormone carrier protein will be studied. Juvenile hormone specific esterases will be purified and characterized and their role in development and differentiation will be investigated. Attempts will be made to find receptors for juvenile hormones in insect target tissue.